With CSS you, yes you, you, the reader, the user, you can override any styles with your custom user style sheet. You can specify general rules for how headers, paragraphs, lists etc. should be rendered across a plethora of web sites. But you can also specify rules that apply to specific sites only. Like, say, my site. On my <body>, I've got the attribute and value id="havard-no-ip-info". With CSS, you can use descendant selectors (or any other contextual selector) to define styles which apply to my site only: